Brackets are used to install recommended dependencies. See http://pythonhosted.org/setuptools/setuptools.html#declaring-extras-optional-features-with-their-own

Brackets are used to install recommended dependencies. See http://pythonhosted.org/setuptools/setuptools.html#declaring-extras-optional-features-with-their-own-dependencies http://pythonhosted.org/setuptools/setuptools.html#declaring... In the case of requests[security], it installs some extra packages that allow for more secure SSL. http://stackoverflow.com/questions/31811949/pip-install-requestssecurity-vs-pip-install-requests-difference http://stackoverflow.com/questions/31811949/pip-install-requ...